Why doesn't the "Disable for viewport selection" button doesn't show up in the Outliner?
Look in the top right of the Outliner tab (in the Default workspace, this appears in the top-right) for a sub-menu called "Restriction Toggles"; it has a symbol that looks a little bit like a triangular key on it. In that sub-menu, you can choose which Restriction Toggles to make visible. By default in 2.80, only Visibility is present, but in this sub-menu you can turn on/off the Selectability, Renderability, etc restrictions toggles as needed.

The Outliner tab appears here in the Default workspace:



Within the Outliner, can find the relevant sub-menu here:



Inside this menu, you can choose from several available Restriction Toggles that you either do or don't want to have appear in your Outliner: